Low PbO-containing glass for electrical devices

Abstract

The invention relates to the glass industry. It concerns glasses of low lead content characterized in being prepared from glass forming batches consisting essentially, in weight percent on the oxide basis of: ______________________________________ SiO 2 66-70 BaO 5-9.5 B 2 O 3 0-3 PbO 1.5-5 Al 2 O 3 2-4.5 MgO + CaO 0-3.5 Li 2 O 0.5-1.6 As 2 O 3 + Sb 2 O 3 0-1 Na 2 O 7-9.5 BaO + MgO + CaO 8-11 K 2 O 5-8.5 Li 2 O + Na 2 O + K 2 O 14.5-17 Na 2 O:K 2 O <1.7 ______________________________________ A specific application of the invention is the fabrication of electrical devices such as light bulbs.

We claim: 
     
       1. Glasses consisting essentially of the following approximate composition: SiO 2  68.75 K 2  O 7.2   Al 2  O 3  2.4 BaO 8.8   Li 2  O 1.0 PbO 3.3   Na 2  O 8.3 Sb 2  O 3  0.25